Idea of growing a new plant culture is ubiquitous among farmers. The dream of every farmer is to find a plant of an unlimited market demand. To achieve this goal many farmers, encouraged with texts from popular magazines, start an experimen-tal cultivation of alternative crops such as medicinal plants. Economic feasibility is the main rationale for a decision to bring a species in cultivation, but it is also a substantial limitation as long as sufficient volumes of material can still be obtained at a lower price from wild harvest (Schippmann et al.2003). The profitability of cultivation of medicinal plants compete with profit achievable for standard field crops for which exist a specialized machinery and standard procedure for applica-tion of fertilizers and agrochemicals to control weeds, pests and diseases. Since MAP are non-standard field crops, even in the first years of the experimental cultivation, it becomes obvious that these plants are labor intensive and that for their successful cultivation is necessary to allocate additional funds to recruit seasonal workers. For successful large scale cultivation of MAPs, high quality raw material should be produced using low input cultivation methods to be com-petitive at the international market and with plants collected from the wild;
alternatively, where much investment is needed to set up cultivation, plant material with a high value should be grown (Lubbe and Verpoorte2011).
The second model for medicinal plants cultivation occurs among small pro-ducers who have arable capacity for which usually is not worthwhile investing into machinery and agrochemicals. This model often attracts people who are, due to transition and economic crisis, jobless looking for some extra sources of the income.
The future market for less known species is highly unpredictable and because many are perennials requiring several years to establish and become harvestable, investment in them could represent a considerable commercial risk (Canter et al.2005). Some additional problems could occur in MAP cultivation, such as slow adaptation of the plant, heterogeneous seed material, pest/disease-susceptible plant populations, and low yields. In reaching the decision on the choice of medicinal plant and the technology of its cultivation, farmers are usually faced with a series of questions for which is difficult to get accurate answers. The most common issues with which the producers of medicinal plants encountered are:
(a) market, (b) abundance and accessibility of wild populations, (c) agro-environmental conditions, (d) labor availability and costs, (e) investments in machinery, (f) post-harvest processing, and (g) rationality of production.
2.1 Market
Forecasting the market trends for herbs is always difficult, due to very large variability in reports and information concerning amount of material in natural populations and plantations. Annual fluctuations in the amount of plants that are normally placed on the market are usually affected by climatic factors, depression due to irrational collection, number of available collectors and profitability of farming (Small2004). It often happens that a new medicinal plant species reach the sudden popularity in the world of herbal pharmacy, followed by dramatic increase in demand for its raw material, resulting in rise in prices on the market.
The high price cause greater collection of natural populations. Since the amount of raw material that can be collected from the wild is limited and heterogeneous in quality, experimental cultivation gets more chances. Cunningham (2001) divided the trend of prices and quantities collected from natural populations of new medicinal plants on the market in four phases (Fig. 8.1). From presented figure can be seen that during the discovery of new medicinal plant and its expansion in pharmaceutical industry, simultaneously raising the amounts of its raw material collected from the wild. Increase in demand is followed by market stabilization, where the price is fixed as well as the offer. This state of the market lasts until the appearance of the offer depression caused by decrease in amounts that can be collected from the wild. Over-exploitation of plant population in nature inevitably leads to their depletion, and consequently to reduced offer. Since at this stage pharmaceutical product is developed assuming that the industry demands for raw
material remain constant, its deficit will causes an increase in the market price, which encourages farmers to start cultivation of the certain plant species. Wiersum et al. (2006) recognized that two types of medicinal plant exploitation could be interrelated with two different conservation strategies: in situ and in domo.
Ros-Tonen and Wiersum (2005) pointed that not only in situ conservation of vulnerable plant species should receive attention, but alsoin domo.
Good examples of conservation through cultivation would be mountain plants which circulate on market in larger quantities, such asGentiana lutea (Franz and Fritz 1978; Bezzi and Aiello 1993; Radanovic´ et al. 2007), Arnica montana (Bomme 1999; Galambosi 2004; Kathe 2006; Pljevljakusic et al. 2014), and Sideritis spp. (Pljevljakusˇic´ et al.2011; Evstatieva and Alipieva2012). Once raw material from cultivation entered, the market offer intends to stabilize, and the prices decline to the point of mutual interests, both of farmers and the pharmaceu-tical industry. At the same time, natural populations could recover through imple-mentation of protection measures in situ conservation, reintroduction or spontaneous regeneration. Consequently, a balance between amounts of raw mate-rials offered from the sustainable collection and from cultivation is reached satis-fying market demand.
Discovery
Expansion Stabilisation
Price
Decline Cultivation
Volume of wild harvest
Recovery Volume of cultivation
Fig. 8.1 Transition phases from wild harvesting to cultivation: after wild resources decline with over-harvesting, raw material prices increase and cultivation becomes economically feasible;
more resilient species can recover (After Cunningham2001)
2.2 Abundance and Accessibility of Wild Populations
When choosing plant species for introduction into the cultivation, beside consider-ation of market issues, farmers usually have to take into account the abundance and accessibility of plant populations in the nature. If a plant species is widespread in the wild, then the interest of the farmer becomes questionable. The collector of wild plants has much lower production costs compared to investments that farmer has. In contrast to the cultivation of medicinal plants, a collector does not have to rent/farm the land and to perform necessary agricultural practices like: obtaining of good quality seeds, seedlings production, deep plowing, fertilizing, soil preparation, planting, watering, hoeing, etc.
In case of highly abundant natural populations, cultivation may be favored only by special requirements of the market, mainly related to strict request of a drug quality, i.e. relatively limited range of the content of particular secondary metab-olite. When significant quantities of raw material are gathered from the wild, such material is mixture of populations differing in the content and composition of bioactive substances. In general, for the most traded species, cultivation is always an option. This is especially worthwhile for plants whose distribution in nature is linked to specific habitats, climate and/or geographic regions, as well as species whose medium- and long term collection could cause risks of endangerment (plants in which underground organs are collected, i.e. roots, tubers, and rhizomes). In case of collecting the underground plant organs, the whole plant is usually pulling out, whereas parts containing buds are not returned back into the soil, to ensure the further reproduction of the plant. This refers to many species, includingGentiana lutea, G. punctata, Althaea officinalis, Carlina acaulis, Symphytum officinalis, Iris germanica, Inula helenium, Ononis spinosa, Petasites hybridus, Polygonum bistorta, Potentilla erecta, Primula veris, Sanicula europea, Sanguisorba officinalis, Saponaria officinalis, and some other European plants.
Especially threatened are “root drug” species growing more or less solitary, i.e. those which not form abundant groups, such as:Gentiana lutea, G. punctata, or Carlina acaulis. Although recognized as internationally important species, many orchids are still harvested for their roots known as “salep” in SEE (mainly Mace-donia, Kosovo, Albania).
In most of the countries there are nature protection laws and legislative on rare and endangered species, whose collection is controlled or in some cases completely forbidden. Naturally, for such species the best conservation strategy is cultivation (e.g. Bomme 1999; Galambosi 2004; Radanovic´ et al. 2007; Pljevljakusˇic´
et al.2011,2014), although many elements of cultivation technology, especially the agro-environmental conditions, are still challenging.
2.3 Agro-environmental Conditions
Regional characteristics for growing a certain crop, depending on the climatic characteristics and soil type, might be treated as an additional key factor in selecting of medicinal plant species for cultivation. It is obvious that some alpine plants cannot tolerate long period of summer temperatures over 20 C, and thus their cultivation is limited to higher altitudes which is especially true for southeast and southern EU countries, and other with a similar climate (yellow gentian, rhodiola, arnica). In some cases herbal industry seeks for a high level of active substances, which accumulate as a result of secondary metabolism, which is closely related to the strategy of survival under stress conditions induced by increased UV radiation i.e. rutin in buckwheat leaf (Kreft et al. 2002). Such plants should be grown at higher altitudes to achieve desired quality of the drug. As a general rule should be stressed that plant varieties which can be grown in the regions of a lower altitudes have a longer vegetation and higher yields than plants grown at higher altitudes, but, on the other hand the latter could have increased accumulation of secondary metabolites per unit mass of herbal drugs. It has been assumed that biosynthesis of most of secondary metabolites is induced by extra-optimal influence of various abiotic and biotic factors (e.g. Pavarini et al.2012). Therefore, in optimal environ-mental conditions, a plant would tend to increase biomass of the photosynthetic organs and to invest into its reproduction, rather than to synthesize secondary metabolites usually needed to cope with stresses.
If this is the case, lower production cost and achievement of higher biomass may compete with the quality. Greater accumulation of secondary metabolites is some-times clearly defined by the market quality criteria and therefore the cultivation of certain MAP species has to be adapted to the prescribed requirements.
The annual amount and distribution of rainfall is one of the key limiting factors in crop production, including MAP. Some medicinal plants for their undisturbed growth and development require a large amount of water (plantain, mint), while for the others too much water in the soil disturbs normal physiology, like forLavandula spp., andMelissa officinalis for example (e.g. Hoffmann1949).
Soil texture is the next limiting factor. For most medicinal plants, in which the drug is underground organ, it is impossible or difficult the cultivation on the soil of a
‘heavy’ texture, including clayey and rocky soils. Also, soils which have a lot of clay and/or silt often have poor water drainage of arable layer and high level of underground water, which could be a limiting factor in production of some medic-inal plant species likeSideritis spp., Helychrisum spp., etc. (e.g. Chittendon1956;
Huxley1992).
Moreover, chemical features of the soil, naturally determine selection of species for cultivation. This refers to soil pH, salinity level and the content of soil macro-and micronutrients. Some of plants successfully grow on low soil pH, while other prefer neutral or slightly-alkaline environment. The same situation is with the species that naturally inhabit the saline habitats, including chamomile, yarrow,
pennyroyal and some others (Dajic-Stevanovic et al.2008,2014), being able for cultivation on slightly salt effected soils.
2.4 Labor Availability and Costs
Unlike conventional farming, cultivation of medicinal plants is carried out on smaller areas. For this reason, the interest of the agro-chemical industry to develop specific programs to protect these crops is small or nil. In the absence of selective agents to combat the weed flora plantation maintenance is usually performed by inter-row cultivation and manual hoeing. Weed pressure on the plot could be significantly reduced by combining agriculturally intensive field crops in the crop-rotation system with herbs and applying glyphosate based herbicide prior to plantation establishment (NMPB 2008). Regarding weed reduction, wheat is the best preceding crop in crop-rotation, since it has range of beneficial effects suitable for the next crop. Wheat has short vegetation, where after the harvest and the shallow plowing many weeds are brought in a good position for growth, which afterwards can be effectively treated with total herbicides (e.g. Dajic-Stevanovic et al.2007). Despite the integral measures against weeds, producer of medicinal plants still must account for hiring of additional seasonal labor for this purpose. In addition, in most herbs some of the process of planting, harvesting and post-harvest processing is not fully automated and therefore this must be taken into account for the required number of seasonal workers. Considering that it has been estimated that seasonal labor in the total sum of production costs relates significant part, right after the cost of energy for drying (Qaas and Schiele2001), proper planning of the number of seasonal workers and the amount of their allowances can be crucial for success of production. The problem of availability and motivation of labor for growing of alternative crops is usually the limiting factor in production of medic-inal plants in hilly-mountain rural areas, due to general depopulation. Unstable situation in terms of availability and costs of labor for field farming should be taken into account when producer is choosing the plots for cultivation of medicinal plants.
Since the problem of labor costs may limit even the best planned plant production, in organization of farm work starting from a seed towards the raw material, producer should strive to increase level of automation of the overall production process.
2.5 Investments in Machinery
Some processes in cultivation of medicinal plants can be facilitated by inclusion of specialized machinery. For some processes it is possible to use the machinery of major crops production in unmodified form, or with some minor modifications.
Thus, for seed processing the existing sieves and cyclones for air-selection could be
used; for direct sowing cereal or pneumatic drills are appropriate; for seedling production the soil block machinery and plastic containers from vegetable produc-tion could be recommended; for planting - planters could be used; harvesting could be done with harvesters or mowers, and for digging of roots potato diggers and ploughs could be a good option. For harvest of some herbs specialized harvesters are used, which could be operational with minor modifications for harvesting of some other medicinal plants. For example, the harvester specialized for chamomile flowers picking, could be used for harvesting of peppermint, lemon balm, and ribwort plantain. Among all herbs, the automation of the production process in case of chamomile has reached the furthest point (Zimmer and Mu¨ller2004). Since investments in machinery, as well as in facilities for drying of the raw material, significantly raise production costs, these additional funds must be justified by the final price of raw materials. Therefore, it is evident that a large cultivation area more quickly justifies resources invested in automation, i.e. machinery. For exam-ple, a standard chamomile harvester can turn 3–4 ha flower in a day, which means that, if the harvest campaign lasts 15 days, it could turn theoretically 45–60 ha (Brkic´ S, personal communication). On the other hand, the capacity for industrial dryers of raw materials is the most common limiting factor, so in this case harvester will almost never work at its full capacity. Nevertheless, the same harvester, after a period of chamomile harvest, could be used with minor modifications to harvest herb in other medicinal crops. For any new investment in the automation of the medicinal plants production process, it is reasonable to carefully calculate pay off of such investment.
2.6 Postharvest Processing
There is a wide range of machinery for postharvest processing of fresh and dry medicinal plants raw material. In case of fresh plant material processing, the most common steps are lines of washing, chopping, and the separation by size, while the processing equipment for dry plant material are mainly used for the separation of the leaf from the stem, machine for flowering stalk cutting (e.g., chamomile), and vibrational or air separators. Some of the postharvest practices are necessary and their absence would cause an irreversible quality loss of raw material. Thus, for example, insufficiently washed roots can dry out in optimal conditions, but the soil residuum on root increases the critical quality parameter - the share of ash (%) and makes raw material useless for further industrial processing. Use of additional facilities, such as choppers and size separators enable more rational use of energy during further drying of raw material. Drying of medicinal and aromatic plants is crucial process in maintaining high quality of herbal drugs. Drying is one of the oldest ways of preserving and processing of food, and also the most important part of primary processing of medicinal plants. It is a process that facilitates the evaporation of water from plant tissues using the heated air flow. The heat may come from the sun or it could be generated by artificial sources, with additional
consumption of some the energy (oil, fuel oil, coal, wood, gas, etc.). In most plants it is easy to gather a large amount of raw material for a short time, but it usually takes much more time to devote to post-harvest processing of plant material. Too fast drying, with applying the additional heat, could cause degradation of the active components in plant tissue. When plants are dried too slowly, this can lead to secondary microbiological infections and the initiation of certain enzyme mecha-nism effects, which may also degrade the desirable active metabolites. Drying costs, besides the cost of wages for seasonal workers, are the largest group of costs (30–50 %) in the production of medicinal plants (Qaas and Schiele2001).
Modern production of high-quality raw medicinal herb, flower and root is inconceivable without the use of industrial dryers. Investing in the packaging does not usually significantly increases the cost of the production, but it is certainly the cost of which the producer should be aware. Warehouses are usually an essential element of infrastructure for the production of medicinal herbs, so when planning the production of large quantities of herbs their construction should be considered.
2.7 Rationality of Production
Taking into account all of the above listed parameters that must be considered carefully during decision making process about investing in the cultivation of medicinal plants, we assume that these parameters can be roughly evaluated according to the presented aspects.
After evaluation of the parameters proposed in of production rationality (IR) could be calculated using the equation:
IR ¼ P þ V þ AE þ Qð Þ= L þ M þ PH þ Tð Þ;
Where P, V, AE, Q, L, M, PH, T, represent Price, Vulnerability, Agro-Ecolog-ical conditions, recognizable Quality, Labor cost, Machinery purchase costs, Post-Harvest (drying) costs and Transport costs, respectively. Each parameter was scored from 1 to 5 (1 – low; 5 – high).
Calculated index values may vary in the range of 0.2–5.
Based on the authors’ experience, an estimation have been made that the ratio of investment and the profit equalized when index of production rationality (IR) is equal to 1, and moreover that most of the plantation of medicinal plants by the index rationality production ranges from 1.3 to 2. If the estimated index of production rationality is less than 1, it should be considered that the selection of MAP brought
Based on the authors’ experience, an estimation have been made that the ratio of investment and the profit equalized when index of production rationality (IR) is equal to 1, and moreover that most of the plantation of medicinal plants by the index rationality production ranges from 1.3 to 2. If the estimated index of production rationality is less than 1, it should be considered that the selection of MAP brought